Climate change, rising concerns about the environment, restrictive regulations regarding emissions, and the development of battery technologies in recent years are driving factors behind the actual growth of electric mobility. Besides the current changes in passenger cars, there have been ongoing changes with regard to buses, delivery vehicles, trucks and construction machines as well. According to EU estimates, this class of vehicles causes 25% of all traffic emissions.
The first all-electric prototypes of established manufacturers are now undergoing testing. Despite the skepticism that a 40-ton truck cannot economically reach the necessary range of batteries, there are battery-run electric buses in the 18 m-class, and trucks with the highest cargo capacity available on international roads.
In addition to the permanent growth in battery capacity, the use of innovative, highly efficient power semiconductors in the drive train extends the range of these vehicles. In contrast to their combustion-driven counterparts, recovering kinetic energy during deceleration plays an important role, particularly during downhill cruising. In the challenging environment of long-distance driving or the uneven terrain of construction sites, there is an increased demand for high-performance power semiconductors that can safely support the lifetime requirements of the application. Trucks and buses are built to last for at least 15 years, and achieve one million kilometers during this period.
Particularly interesting for trucks: Platooning – stringing a number of trucks together to form a road train – is a further option to reduce fuel consumption. Eliminating energy-intense maneuvers and reducing the air drag in the slipstream is beneficial. For safety reasons, intense communication between the (ideally automated) participants is mandatory. This demands high-speed communications like 5G, accurate 2- and 3D-imaging as well as highly reliable subsystems in drive-by-wire and break-by-wire scenarios with automated steering and acceleration. Even if the power consumption in these safety-relevant systems is far lower than in the drive train, they place even higher demands on power electronic components, driver technologies, microcontrollers and sensors.
With the upcoming technology of fully automated, driver-less designs, new challenges for the charging infrastructure of heavy-duty vehicles arise as well. Driven by the computer, regular breaks for the driver become obsolete, and minimizing charging pauses for the vehicle is desired. Current standardization committees are discussing battery voltages up to 1500 A allowing charging currents up to 3000 A. This resembles a charging power level of up to 4.5 MW. Buses and trucks, as a rule of thumb, consume about one kWh/km. At four MW, the energy required to drive 400 further kilometers can be delivered in about six minutes, theoretically.
With power levels this high, the efficiency of energy conversion becomes even more important. Unnecessary losses demand more intense cooling, which, in turn, increases the cost of operation. Therefore, modern wide-bandgap semiconductors based on SiC are a promising technology in this field of application.
"There is an increased demand for high-performance power semiconductors for the e-mobility of commercial vehicles. "
- Power semiconductor devices